Chaos in known to be useful. In fact, under certain conditions, it is a desirable feature of systems and circuits. The dynamical richness of chaotic behavior has significant potential applications to real-world problems, including secure communications, persistent excitation, information processing and incryption, to mention but a few (Ott, 2002 “Chaos in Dynamical Systems (Cambridge University Press, UK); Strogatz, S. H. 2001 “Nonlinear Dynamics, and Chaos: with applications to physics, biology, chemistry, and engineering (Westview Press, USA)); Tam et al., 2007 “Communications with Chaos: Multiple access techniques and performance (Elsevier Science Press, Great Britain)). In particular, the present invention uses chaos theory to design a reconfigurable multivibrator element in order to have different configurations in an all-in-one circuit.
A multivibrator circuit is a simple two-state system that has only one of three possible configurations, these are:
(i) Astable multivibrator, in this configuration, both states of the system are unstable. As a consequence, the output of the circuit spends a given amount of time in one state, and then in the other, moving back and forth from one to the other in a continuously repeated cycle. Usually, this configuration is used to generate sequences and pulses with a given frequency and width, see for example patents JP53085479, U.S. Pat. No. 4,191,927.
(ii) Monostable multivibrator, in this configuration, one state of the circuit is stable while the other is unstable. As such, the system may spend some time in the unstable state, but eventually will move into the stable state and remain there afterwards. This configuration can be used, for instance, to define a time-period of activity measured from an event, for example in JP57044768, U.S. Pat. No. 4,430,682 monostable multivibrators are used in motor timing.
(iii) Bistable multivibrator, in this configuration both states are stable. This implies that the circuit remains in its current state, until being forced to change to the other by an external event or input. A multivibrator system in bistable configuration can be used as a fundamental building block of a register or memory device, for example in U.S. Pat. Nos. 4,081,840 and 4,191,927, a bistable multivibrator in used as part of a switching device.
There is great interest in developing new working paradigms to complement and even replace current statically configurable architectures. One of the newest ideas is chaos computing which focuses on the development of devices with dynamic logic architecture and employs nonlinear or chaotic elements in logic operations. Application of chaos computing requires the development of dynamic logic gates (also called logic cells) that are able to change their response according to threshold reference signals and offset signals in order to produce different logic gates. These dynamic logic gates would support development of logic chips for next generation computers. Current inventions related to logic gates that exploit features of nonlinear dynamic systems through their electronic implementations are, for example, U.S. Pat. Nos. 8,091,062, 7,973,566, 7,924,059, 7,863,937, 7,415,683, 7,096,437, 7,453,285, 7,925,814, 7,925,131 and US patent application 2010/0219858. These inventions make use of chaotic computing architectures based on nonlinear elements, while the present invention discloses reconfigurable multivibrator using a nonlinear oscillator.
Reconfigurable structures based on chaos have been investigated for a long time, with significant results, such as: [Cafagna, D. & Grassi, G. 2005. “Chaos-based computation via Chua's circuit: Parallel computing with application to the SR flip-flop,” Int. Symp. Sign. Circuits Syst. 2, 749-752.] where the chaotic Chua's circuit use it to obtain two logic gates from two state variables, from those chaos-based logic they implemented two NOR gates and build a standard flip-flop device. Alternative realizations of chaos-based logic gate have been reported [Sinha, S. & Ditto, W. 1998 “Dynamics based computations,” Phys. Rev. Lett. 81, 2156-2159; Murali K., Sudeshna S. 2003 “Experimental realization of chaos control by thresholding”, Physical Review E., vol. 68, Jul. 14, 2003; Campos-Cantón E., J. G. Barajas-Ramírez, G. Solís-Perales, R. Femat, 2010, “Multiscroll attractors by switching systems”. CHAOS, 20: 013116]. With these logic gates is possible to build just a static bistable multivibrator.
Different methods for the construction of multivibrators have been disclosed, for example U.S. Pat. Nos. 6,281,732, 4,301,427, and GB1416931 describe constructions of astable, monostable and bistable multivibrators based on stabilized amplifiers, mosfets and inverters. However, unlike the present invention these multivibrators have fixed configurations, without the possibility of reconfiguration. In many applications of multivibrators more than one configuration is required, for example in devices for measurement and control of temperature, acoustic, and motor timing (see patents U.S. Pat. No. 4,081,840, U.S. Pat. No. 731,082, JP53085479). In these inventions it is compulsory to combine more than one multivibrator configuration. The reconfigurable multivibrator provided in the present invention discloses a single device to obtain an all-in-one multivibrator configuration (monostable, astable, and bistable).